The present invention relates to an improved magnetically guided vehicle. In the prior art, devices are known whereby a vehicle or other device is guided through the use of magnetic guidance structure. However, Applicant is unaware of any such device which includes all of the various aspects and nuances of present invention. The following prior art is known to Applicant:
U.S. Pat. No. 2,690,626 to Gay et al. discloses a steering means for toys comprising, essentially, a magnet and steering wheel pivotally mounted so as to follow a track which may consist of a strip of flexible tape containing iron particles. The present invention differs from the teachings of Gay et al. for several reasons including the use of a bar code and bar code reader, as well as the inclusion of sophisticated guidance structure.
U.S. Pat. No. 3,474,877 to Wesener discloses an automatically guided vehicle installation wherein guide means may be a simple band or tape of ferromagnetic material. Additional code markings may be provided for reading by appropriate means on the vehicle to provide specific instructions. The present invention differs from the teachings of this patent as including guidance and sensing structure nowhere taught or suggested by Wesener.
U.S. Pat. No. 3,550,716 to Wickstrom discloses an automobile speed controlling mechanism wherein sensors on a vehicle respond to signals derived by passing through magnetic fields located on a roadway. The system may include strips having a magnetizable print or a preformed polymeric sheet having particles embedded therein.
U.S. Pat. No. 3,575,255 also to Wickstrom discloses further refinements of U.S. Pat. No. 3,550,716. The present invention differs from the teachings of these patents in that the Wickstrom patents are specifically directed to a speed controlling system, whereas the present invention is directed to guidance of a vehicle without the necessity of speed control.
U.S. Pat. No. 3,609,678 to Fayling discloses magnetized means for providing control information to moving vehicles, wherein the means comprises polymer magnets preferably in the form of a sheet or tape and arranged in geometrics or magnetized in patterns to provide specific information. The present invention differs from the teachings of Fayling in that the present invention includes sensing and guidance control means nowhere taught or suggested in Fayling, and further, the Fayling device is intended to be used on a roadway, whereas the present invention is designed to be used on a floor surface.
U.S. Pat. No. 3,653,456 to Uemura discloses a control system for moving vehicles along a predetermined path which may be a strip of magnetic material providing a flux source which may be sensed by structure of the vehicle. The present invention differs from the teachings of Uemura in that Uemura specifically discloses an air-gap head for sensing, which structure is different from the teachings of the present invention.
U.S. Pat. Nos. 3,245,493 to Barrett, Jr., 4,003,445 to De Bruine, 4,593,238 to Yamamoto and 4,593,239 to Yamamoto disclose position location means, either magnetic or optical, as well as separate detection means on a vehicle designed to receive location information from code markers located on one or both sides of a guide path. The present invention differs from the teachings of these patents for the following reasons: with regard to Barrett, Jr., this patent discloses wire guidance which is different from the teachings of the present invention; De Bruine teaches the use of bar codes on the actual path with optical reading means, whereas the present invention discloses magnetic reading means and a magnetized bar code separate from the path and designed to be read by the magnetic bar code reading means to tell the vehicle the configuration of the path; Yamamoto '238 discloses an optical sensor array for stopping a vehicle rather than steering the vehicle; Yamamoto '239 also discloses optical guidance means which is different from the magnetic guidance means of the present invention.
The following U.S. patents include sensing means employed to detect a guide path: 3,669,205 to Brooke (tuned coils responding to a magnetic guide path and wire guidance); 4,714,124 to Laib (Hall effect sensors and wire guidance); 4,566,032 to Hirooka et al. (bar code reading and vision system); 4,777,601 to Boegli (optical sensor).
U.S. Pat. Nos. 3,628,624 to Wesener; 4,015,680 to Pircher et al. and 4,800,978 to Wasa et al. disclose multiple sensors mounted in an array. The sensor arrays as disclosed in these patents provide longitudinal and lateral stability in relation to the guide path by means of sensors in the array being placed in line with and on either side of the guide path such that detection of the path by the outer sensor triggers a steering signal to put the vehicle back on track. Pircher et al., in particular, disclose outer scanning elements positioned at increasing distances from a central element, with the outer elements triggering a greater steering deflection than the inner elements. Concerning these references, Pircher et al. do not disclose a specific preferred guide path material. Wasa et al. disclose the use of an inductive path rather than a permanent magnet path.
U.S. Pat. Nos. 4,345,662 to Deplante and 4,716,530 to Ogawa et al. disclose inclusion in one vehicle system of multiple guide means. Deplante provides an optical guide path and detection means coupled with an ultrasonic emitter-receiver assembly for obstacle detection. Ogawa et al. combine a magnetic guide path comprising a guide wire with optical location markers in particular patterns which provide data instructions for speed and route.
The teachings of these references differ from the teachings of the present invention as will be described in greater detail hereinbelow.